1. Field of the Invention
The invention relates generally to efficient means for the generation of electrical or other power utilizing energy from subterranean geothermal sources and, more particularly, relates to novel bearing and bearing lubrication arrangements for providing long-life and efficient deep well heat exchange and pumping equipment finding application in deep, hot brine wells for the transfer of thermal energy for use at the earth's surface.
2. Description of the Prior Art
A basic advance in the geothermal power extraction art, not limited to use with the rare dry steam geothermal sources and also devoid of the steam and geothermal brine separation problem and the consequent corrosion problems attached to prior art systems using mixed steam and hot water supply wells, was presented in the H. B. Matthews U.S. Pat. No. 3,824,793, issued Oct. 24, 1972 for a "Geothermal System and Method", and in the divisional application which resulted in the U.S. Pat. No. 3,898,020 of the same title, issued May 8, 1974.
Improvements in the basic Matthews concept appear in more recently filed U.S. patents, also assigned to Sperry Rand Corporation:
K. e. nichols et al. U.S. Pat. No. 3,905,196, issued Sept. 16, 1975 for a "Geothermal Energy Pump Thrust Balance Apparatus", PA1 J. l. lobach U.S. Pat. No. 3,908,380, issued Sept. 30, 1975 for a "Geothermal Energy Turbine and Well System", and PA1 H. b. matthews et al. U.S. Pat. No. 3,910,050, issued Oct. 7, 1975 for a "Geothermal Energy System and Control Apparatus". The five aforementioned patents disclose geothermal energy recovery systems making use of thermal energy stored by subterranean heat sources in hot, solute-bearing well water to generate super-heated steam from a surface-injected flow of clean water; the super-heated system is then used to operate a turbine-driven pump within the well for pumping the hot brine at high pressure and always in liquid state to the earth's surface, where it transfers its heat in a binary closed-loop heat exchanger-vapor turbine-alternator combination for generation of electrical power. Residual brine is pumped back into the earth, while the clean, cooled water is regenerated at the surface-located system and is returned to the deep well pumping system for generating steam and also for lubrication of fluid bearings supporting the turbine-driven pump system. The latter three patents concern a similar system, illustrating improvement features in the form of hydrodynamic radial and thrust bearings and pressurized liquid bearing lubrication means. A reverse flow, deep well steam turbine motor of compact nature is also disclosed, along with features of the surface control and power generation systems.
In the H. B. Matthews U.S. patent application Ser. No. 674,243 for a "Geothermal Energy Conversion System", filed Apr. 6, 1976 and also assigned to Sperry Rand Corporation, there is disclosed a further improvement in geothermal energy extraction systems which reduces the initial and operating costs of the apparatus, eliminating certain surface and down-well elements and providing apparatus of reduced complexity and considerably enhanced efficiency. This latter gravity head geothermal energy recovery system makes use of thermal energy stored in hot, solute-bearing well water particularly during the period that is pumped upward to the earth's surface through an extended lineal heat exchange element for continuously heating a downward flowing organic working fluid. The added energy of the latter fluid is then used within the well for operating a turbine-driven pump for pumping the hot, solute-bearing well water at high pressure and always in liquid state to the earth's surface, where it is reinjected into the earth by a sump well. The temperature difference between the upward flowing brine and the downward flowing organic working fluid is maintained along the length of the subterranean extended heat exchange element. After driving the deep well turbine-driven pump, the organic fluid arises to the earth's surface in a thermally insulated conduit. At the earth's surface, electrical power generating equipment is driven by the ascended organic fluid, after which it is returned into the well for reheating as it travels downward in the extended heat exchanger.